Wall Teichoic Acids (WTA) are found in many Gram-positive bacteria and consist of an anionic, phosphate rich polymer that is cross-linked to cell surface peptidoglycan. WTAs have many functions including maintaining the integrity of the cellular envelope. In Bacillus subtilis strain 168, the polymer portion of Wall Teichoic Acids contains glycerol phosphate, while in B. subtilis strain W23 and Staphylococcus aureus strains, the WTA polymer contains ribitol phosphate. Much of what is known about the S. aureus pathway is based on the B. subtilis strain W23 model. In S. aureus, WTAs play an essential role in adhesion to endothelial and epithelial tissues. WTAs have also been found to be critical for colonization in numerous infection models. A better understanding of the biosynthesis of WTAs will provide tools for making antimicrobials that target this pathway.
The development of antimicrobials effective against S. aureus is of particular importance. Invasive Methicillin-resistant Staphylococcus aureus (MRSA) infections have become a major public health problem, causing 94,000 life-threatening infections in 2005, of which almost 19,000 resulted in death. (N. K. Peters, D. M. Dixon, S. M. Holland, A. S. Fauci, (2008) Journal of Infectious Diseases 197, 1087) Recently, strains carrying genes encoding resistance to vancomycin, the “last resort” antibiotic for these infections, have begun to appear. (D. M. Sievert et al., (2008) Clinical Infectious Diseases 46, 668) New antibiotics to treat MRSA infections have been introduced recently, but as expected, clinical resistance has already been observed. (W. Witte et al., (2008) International Journal of Medical Microbiology 298, 365) It is imperative to continue discovering new targets and strategies to combat multi-drug resistant pathogens.